]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blobdiff - zfs/module/zfs/dsl_dir.c
UBUNTU: SAUCE: (noup) Update spl to 0.6.5.9-1, zfs to 0.6.5.9-2
[mirror_ubuntu-artful-kernel.git] / zfs / module / zfs / dsl_dir.c
diff --git a/zfs/module/zfs/dsl_dir.c b/zfs/module/zfs/dsl_dir.c
new file mode 100644 (file)
index 0000000..762e2e5
--- /dev/null
@@ -0,0 +1,2009 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
+ * Copyright (c) 2013 Martin Matuska. All rights reserved.
+ * Copyright (c) 2014 Joyent, Inc. All rights reserved.
+ * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
+ * Copyright (c) 2016 Actifio, Inc. All rights reserved.
+ */
+
+#include <sys/dmu.h>
+#include <sys/dmu_objset.h>
+#include <sys/dmu_tx.h>
+#include <sys/dsl_dataset.h>
+#include <sys/dsl_dir.h>
+#include <sys/dsl_prop.h>
+#include <sys/dsl_synctask.h>
+#include <sys/dsl_deleg.h>
+#include <sys/dmu_impl.h>
+#include <sys/spa.h>
+#include <sys/metaslab.h>
+#include <sys/zap.h>
+#include <sys/zio.h>
+#include <sys/arc.h>
+#include <sys/sunddi.h>
+#include <sys/zfeature.h>
+#include <sys/policy.h>
+#include <sys/zfs_znode.h>
+#include <sys/zvol.h>
+#include "zfs_namecheck.h"
+#include "zfs_prop.h"
+
+/*
+ * Filesystem and Snapshot Limits
+ * ------------------------------
+ *
+ * These limits are used to restrict the number of filesystems and/or snapshots
+ * that can be created at a given level in the tree or below. A typical
+ * use-case is with a delegated dataset where the administrator wants to ensure
+ * that a user within the zone is not creating too many additional filesystems
+ * or snapshots, even though they're not exceeding their space quota.
+ *
+ * The filesystem and snapshot counts are stored as extensible properties. This
+ * capability is controlled by a feature flag and must be enabled to be used.
+ * Once enabled, the feature is not active until the first limit is set. At
+ * that point, future operations to create/destroy filesystems or snapshots
+ * will validate and update the counts.
+ *
+ * Because the count properties will not exist before the feature is active,
+ * the counts are updated when a limit is first set on an uninitialized
+ * dsl_dir node in the tree (The filesystem/snapshot count on a node includes
+ * all of the nested filesystems/snapshots. Thus, a new leaf node has a
+ * filesystem count of 0 and a snapshot count of 0. Non-existent filesystem and
+ * snapshot count properties on a node indicate uninitialized counts on that
+ * node.) When first setting a limit on an uninitialized node, the code starts
+ * at the filesystem with the new limit and descends into all sub-filesystems
+ * to add the count properties.
+ *
+ * In practice this is lightweight since a limit is typically set when the
+ * filesystem is created and thus has no children. Once valid, changing the
+ * limit value won't require a re-traversal since the counts are already valid.
+ * When recursively fixing the counts, if a node with a limit is encountered
+ * during the descent, the counts are known to be valid and there is no need to
+ * descend into that filesystem's children. The counts on filesystems above the
+ * one with the new limit will still be uninitialized, unless a limit is
+ * eventually set on one of those filesystems. The counts are always recursively
+ * updated when a limit is set on a dataset, unless there is already a limit.
+ * When a new limit value is set on a filesystem with an existing limit, it is
+ * possible for the new limit to be less than the current count at that level
+ * since a user who can change the limit is also allowed to exceed the limit.
+ *
+ * Once the feature is active, then whenever a filesystem or snapshot is
+ * created, the code recurses up the tree, validating the new count against the
+ * limit at each initialized level. In practice, most levels will not have a
+ * limit set. If there is a limit at any initialized level up the tree, the
+ * check must pass or the creation will fail. Likewise, when a filesystem or
+ * snapshot is destroyed, the counts are recursively adjusted all the way up
+ * the initizized nodes in the tree. Renaming a filesystem into different point
+ * in the tree will first validate, then update the counts on each branch up to
+ * the common ancestor. A receive will also validate the counts and then update
+ * them.
+ *
+ * An exception to the above behavior is that the limit is not enforced if the
+ * user has permission to modify the limit. This is primarily so that
+ * recursive snapshots in the global zone always work. We want to prevent a
+ * denial-of-service in which a lower level delegated dataset could max out its
+ * limit and thus block recursive snapshots from being taken in the global zone.
+ * Because of this, it is possible for the snapshot count to be over the limit
+ * and snapshots taken in the global zone could cause a lower level dataset to
+ * hit or exceed its limit. The administrator taking the global zone recursive
+ * snapshot should be aware of this side-effect and behave accordingly.
+ * For consistency, the filesystem limit is also not enforced if the user can
+ * modify the limit.
+ *
+ * The filesystem and snapshot limits are validated by dsl_fs_ss_limit_check()
+ * and updated by dsl_fs_ss_count_adjust(). A new limit value is setup in
+ * dsl_dir_activate_fs_ss_limit() and the counts are adjusted, if necessary, by
+ * dsl_dir_init_fs_ss_count().
+ *
+ * There is a special case when we receive a filesystem that already exists. In
+ * this case a temporary clone name of %X is created (see dmu_recv_begin). We
+ * never update the filesystem counts for temporary clones.
+ *
+ * Likewise, we do not update the snapshot counts for temporary snapshots,
+ * such as those created by zfs diff.
+ */
+
+extern inline dsl_dir_phys_t *dsl_dir_phys(dsl_dir_t *dd);
+
+static uint64_t dsl_dir_space_towrite(dsl_dir_t *dd);
+
+static void
+dsl_dir_evict(void *dbu)
+{
+       dsl_dir_t *dd = dbu;
+       int t;
+       ASSERTV(dsl_pool_t *dp = dd->dd_pool);
+
+       dd->dd_dbuf = NULL;
+
+       for (t = 0; t < TXG_SIZE; t++) {
+               ASSERT(!txg_list_member(&dp->dp_dirty_dirs, dd, t));
+               ASSERT(dd->dd_tempreserved[t] == 0);
+               ASSERT(dd->dd_space_towrite[t] == 0);
+       }
+
+       if (dd->dd_parent)
+               dsl_dir_async_rele(dd->dd_parent, dd);
+
+       spa_async_close(dd->dd_pool->dp_spa, dd);
+
+       /*
+        * The props callback list should have been cleaned up by
+        * objset_evict().
+        */
+       list_destroy(&dd->dd_prop_cbs);
+       mutex_destroy(&dd->dd_lock);
+       kmem_free(dd, sizeof (dsl_dir_t));
+}
+
+int
+dsl_dir_hold_obj(dsl_pool_t *dp, uint64_t ddobj,
+    const char *tail, void *tag, dsl_dir_t **ddp)
+{
+       dmu_buf_t *dbuf;
+       dsl_dir_t *dd;
+       int err;
+
+       ASSERT(dsl_pool_config_held(dp));
+
+       err = dmu_bonus_hold(dp->dp_meta_objset, ddobj, tag, &dbuf);
+       if (err != 0)
+               return (err);
+       dd = dmu_buf_get_user(dbuf);
+#ifdef ZFS_DEBUG
+       {
+               dmu_object_info_t doi;
+               dmu_object_info_from_db(dbuf, &doi);
+               ASSERT3U(doi.doi_bonus_type, ==, DMU_OT_DSL_DIR);
+               ASSERT3U(doi.doi_bonus_size, >=, sizeof (dsl_dir_phys_t));
+       }
+#endif
+       if (dd == NULL) {
+               dsl_dir_t *winner;
+
+               dd = kmem_zalloc(sizeof (dsl_dir_t), KM_SLEEP);
+               dd->dd_object = ddobj;
+               dd->dd_dbuf = dbuf;
+               dd->dd_pool = dp;
+               mutex_init(&dd->dd_lock, NULL, MUTEX_DEFAULT, NULL);
+
+               list_create(&dd->dd_prop_cbs, sizeof (dsl_prop_cb_record_t),
+                   offsetof(dsl_prop_cb_record_t, cbr_node));
+
+               dsl_dir_snap_cmtime_update(dd);
+
+               if (dsl_dir_phys(dd)->dd_parent_obj) {
+                       err = dsl_dir_hold_obj(dp,
+                           dsl_dir_phys(dd)->dd_parent_obj, NULL, dd,
+                           &dd->dd_parent);
+                       if (err != 0)
+                               goto errout;
+                       if (tail) {
+#ifdef ZFS_DEBUG
+                               uint64_t foundobj;
+
+                               err = zap_lookup(dp->dp_meta_objset,
+                                   dsl_dir_phys(dd->dd_parent)->
+                                   dd_child_dir_zapobj, tail,
+                                   sizeof (foundobj), 1, &foundobj);
+                               ASSERT(err || foundobj == ddobj);
+#endif
+                               (void) strcpy(dd->dd_myname, tail);
+                       } else {
+                               err = zap_value_search(dp->dp_meta_objset,
+                                   dsl_dir_phys(dd->dd_parent)->
+                                   dd_child_dir_zapobj,
+                                   ddobj, 0, dd->dd_myname);
+                       }
+                       if (err != 0)
+                               goto errout;
+               } else {
+                       (void) strcpy(dd->dd_myname, spa_name(dp->dp_spa));
+               }
+
+               if (dsl_dir_is_clone(dd)) {
+                       dmu_buf_t *origin_bonus;
+                       dsl_dataset_phys_t *origin_phys;
+
+                       /*
+                        * We can't open the origin dataset, because
+                        * that would require opening this dsl_dir.
+                        * Just look at its phys directly instead.
+                        */
+                       err = dmu_bonus_hold(dp->dp_meta_objset,
+                           dsl_dir_phys(dd)->dd_origin_obj, FTAG,
+                           &origin_bonus);
+                       if (err != 0)
+                               goto errout;
+                       origin_phys = origin_bonus->db_data;
+                       dd->dd_origin_txg =
+                           origin_phys->ds_creation_txg;
+                       dmu_buf_rele(origin_bonus, FTAG);
+               }
+
+               dmu_buf_init_user(&dd->dd_dbu, dsl_dir_evict, &dd->dd_dbuf);
+               winner = dmu_buf_set_user_ie(dbuf, &dd->dd_dbu);
+               if (winner != NULL) {
+                       if (dd->dd_parent)
+                               dsl_dir_rele(dd->dd_parent, dd);
+                       mutex_destroy(&dd->dd_lock);
+                       kmem_free(dd, sizeof (dsl_dir_t));
+                       dd = winner;
+               } else {
+                       spa_open_ref(dp->dp_spa, dd);
+               }
+       }
+
+       /*
+        * The dsl_dir_t has both open-to-close and instantiate-to-evict
+        * holds on the spa.  We need the open-to-close holds because
+        * otherwise the spa_refcnt wouldn't change when we open a
+        * dir which the spa also has open, so we could incorrectly
+        * think it was OK to unload/export/destroy the pool.  We need
+        * the instantiate-to-evict hold because the dsl_dir_t has a
+        * pointer to the dd_pool, which has a pointer to the spa_t.
+        */
+       spa_open_ref(dp->dp_spa, tag);
+       ASSERT3P(dd->dd_pool, ==, dp);
+       ASSERT3U(dd->dd_object, ==, ddobj);
+       ASSERT3P(dd->dd_dbuf, ==, dbuf);
+       *ddp = dd;
+       return (0);
+
+errout:
+       if (dd->dd_parent)
+               dsl_dir_rele(dd->dd_parent, dd);
+       mutex_destroy(&dd->dd_lock);
+       kmem_free(dd, sizeof (dsl_dir_t));
+       dmu_buf_rele(dbuf, tag);
+       return (err);
+}
+
+void
+dsl_dir_rele(dsl_dir_t *dd, void *tag)
+{
+       dprintf_dd(dd, "%s\n", "");
+       spa_close(dd->dd_pool->dp_spa, tag);
+       dmu_buf_rele(dd->dd_dbuf, tag);
+}
+
+/*
+ * Remove a reference to the given dsl dir that is being asynchronously
+ * released.  Async releases occur from a taskq performing eviction of
+ * dsl datasets and dirs.  This process is identical to a normal release
+ * with the exception of using the async API for releasing the reference on
+ * the spa.
+ */
+void
+dsl_dir_async_rele(dsl_dir_t *dd, void *tag)
+{
+       dprintf_dd(dd, "%s\n", "");
+       spa_async_close(dd->dd_pool->dp_spa, tag);
+       dmu_buf_rele(dd->dd_dbuf, tag);
+}
+
+/* buf must be long enough (MAXNAMELEN + strlen(MOS_DIR_NAME) + 1 should do) */
+void
+dsl_dir_name(dsl_dir_t *dd, char *buf)
+{
+       if (dd->dd_parent) {
+               dsl_dir_name(dd->dd_parent, buf);
+               (void) strcat(buf, "/");
+       } else {
+               buf[0] = '\0';
+       }
+       if (!MUTEX_HELD(&dd->dd_lock)) {
+               /*
+                * recursive mutex so that we can use
+                * dprintf_dd() with dd_lock held
+                */
+               mutex_enter(&dd->dd_lock);
+               (void) strcat(buf, dd->dd_myname);
+               mutex_exit(&dd->dd_lock);
+       } else {
+               (void) strcat(buf, dd->dd_myname);
+       }
+}
+
+/* Calculate name length, avoiding all the strcat calls of dsl_dir_name */
+int
+dsl_dir_namelen(dsl_dir_t *dd)
+{
+       int result = 0;
+
+       if (dd->dd_parent) {
+               /* parent's name + 1 for the "/" */
+               result = dsl_dir_namelen(dd->dd_parent) + 1;
+       }
+
+       if (!MUTEX_HELD(&dd->dd_lock)) {
+               /* see dsl_dir_name */
+               mutex_enter(&dd->dd_lock);
+               result += strlen(dd->dd_myname);
+               mutex_exit(&dd->dd_lock);
+       } else {
+               result += strlen(dd->dd_myname);
+       }
+
+       return (result);
+}
+
+static int
+getcomponent(const char *path, char *component, const char **nextp)
+{
+       char *p;
+
+       if ((path == NULL) || (path[0] == '\0'))
+               return (SET_ERROR(ENOENT));
+       /* This would be a good place to reserve some namespace... */
+       p = strpbrk(path, "/@");
+       if (p && (p[1] == '/' || p[1] == '@')) {
+               /* two separators in a row */
+               return (SET_ERROR(EINVAL));
+       }
+       if (p == NULL || p == path) {
+               /*
+                * if the first thing is an @ or /, it had better be an
+                * @ and it had better not have any more ats or slashes,
+                * and it had better have something after the @.
+                */
+               if (p != NULL &&
+                   (p[0] != '@' || strpbrk(path+1, "/@") || p[1] == '\0'))
+                       return (SET_ERROR(EINVAL));
+               if (strlen(path) >= MAXNAMELEN)
+                       return (SET_ERROR(ENAMETOOLONG));
+               (void) strcpy(component, path);
+               p = NULL;
+       } else if (p[0] == '/') {
+               if (p - path >= MAXNAMELEN)
+                       return (SET_ERROR(ENAMETOOLONG));
+               (void) strncpy(component, path, p - path);
+               component[p - path] = '\0';
+               p++;
+       } else if (p[0] == '@') {
+               /*
+                * if the next separator is an @, there better not be
+                * any more slashes.
+                */
+               if (strchr(path, '/'))
+                       return (SET_ERROR(EINVAL));
+               if (p - path >= MAXNAMELEN)
+                       return (SET_ERROR(ENAMETOOLONG));
+               (void) strncpy(component, path, p - path);
+               component[p - path] = '\0';
+       } else {
+               panic("invalid p=%p", (void *)p);
+       }
+       *nextp = p;
+       return (0);
+}
+
+/*
+ * Return the dsl_dir_t, and possibly the last component which couldn't
+ * be found in *tail.  The name must be in the specified dsl_pool_t.  This
+ * thread must hold the dp_config_rwlock for the pool.  Returns NULL if the
+ * path is bogus, or if tail==NULL and we couldn't parse the whole name.
+ * (*tail)[0] == '@' means that the last component is a snapshot.
+ */
+int
+dsl_dir_hold(dsl_pool_t *dp, const char *name, void *tag,
+    dsl_dir_t **ddp, const char **tailp)
+{
+       char *buf;
+       const char *spaname, *next, *nextnext = NULL;
+       int err;
+       dsl_dir_t *dd;
+       uint64_t ddobj;
+
+       buf = kmem_alloc(MAXNAMELEN, KM_SLEEP);
+       err = getcomponent(name, buf, &next);
+       if (err != 0)
+               goto error;
+
+       /* Make sure the name is in the specified pool. */
+       spaname = spa_name(dp->dp_spa);
+       if (strcmp(buf, spaname) != 0) {
+               err = SET_ERROR(EXDEV);
+               goto error;
+       }
+
+       ASSERT(dsl_pool_config_held(dp));
+
+       err = dsl_dir_hold_obj(dp, dp->dp_root_dir_obj, NULL, tag, &dd);
+       if (err != 0) {
+               goto error;
+       }
+
+       while (next != NULL) {
+               dsl_dir_t *child_dd;
+               err = getcomponent(next, buf, &nextnext);
+               if (err != 0)
+                       break;
+               ASSERT(next[0] != '\0');
+               if (next[0] == '@')
+                       break;
+               dprintf("looking up %s in obj%lld\n",
+                   buf, dsl_dir_phys(dd)->dd_child_dir_zapobj);
+
+               err = zap_lookup(dp->dp_meta_objset,
+                   dsl_dir_phys(dd)->dd_child_dir_zapobj,
+                   buf, sizeof (ddobj), 1, &ddobj);
+               if (err != 0) {
+                       if (err == ENOENT)
+                               err = 0;
+                       break;
+               }
+
+               err = dsl_dir_hold_obj(dp, ddobj, buf, tag, &child_dd);
+               if (err != 0)
+                       break;
+               dsl_dir_rele(dd, tag);
+               dd = child_dd;
+               next = nextnext;
+       }
+
+       if (err != 0) {
+               dsl_dir_rele(dd, tag);
+               goto error;
+       }
+
+       /*
+        * It's an error if there's more than one component left, or
+        * tailp==NULL and there's any component left.
+        */
+       if (next != NULL &&
+           (tailp == NULL || (nextnext && nextnext[0] != '\0'))) {
+               /* bad path name */
+               dsl_dir_rele(dd, tag);
+               dprintf("next=%p (%s) tail=%p\n", next, next?next:"", tailp);
+               err = SET_ERROR(ENOENT);
+       }
+       if (tailp != NULL)
+               *tailp = next;
+       *ddp = dd;
+error:
+       kmem_free(buf, MAXNAMELEN);
+       return (err);
+}
+
+/*
+ * If the counts are already initialized for this filesystem and its
+ * descendants then do nothing, otherwise initialize the counts.
+ *
+ * The counts on this filesystem, and those below, may be uninitialized due to
+ * either the use of a pre-existing pool which did not support the
+ * filesystem/snapshot limit feature, or one in which the feature had not yet
+ * been enabled.
+ *
+ * Recursively descend the filesystem tree and update the filesystem/snapshot
+ * counts on each filesystem below, then update the cumulative count on the
+ * current filesystem. If the filesystem already has a count set on it,
+ * then we know that its counts, and the counts on the filesystems below it,
+ * are already correct, so we don't have to update this filesystem.
+ */
+static void
+dsl_dir_init_fs_ss_count(dsl_dir_t *dd, dmu_tx_t *tx)
+{
+       uint64_t my_fs_cnt = 0;
+       uint64_t my_ss_cnt = 0;
+       dsl_pool_t *dp = dd->dd_pool;
+       objset_t *os = dp->dp_meta_objset;
+       zap_cursor_t *zc;
+       zap_attribute_t *za;
+       dsl_dataset_t *ds;
+
+       ASSERT(spa_feature_is_active(dp->dp_spa, SPA_FEATURE_FS_SS_LIMIT));
+       ASSERT(dsl_pool_config_held(dp));
+       ASSERT(dmu_tx_is_syncing(tx));
+
+       dsl_dir_zapify(dd, tx);
+
+       /*
+        * If the filesystem count has already been initialized then we
+        * don't need to recurse down any further.
+        */
+       if (zap_contains(os, dd->dd_object, DD_FIELD_FILESYSTEM_COUNT) == 0)
+               return;
+
+       zc = kmem_alloc(sizeof (zap_cursor_t), KM_SLEEP);
+       za = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
+
+       /* Iterate my child dirs */
+       for (zap_cursor_init(zc, os, dsl_dir_phys(dd)->dd_child_dir_zapobj);
+           zap_cursor_retrieve(zc, za) == 0; zap_cursor_advance(zc)) {
+               dsl_dir_t *chld_dd;
+               uint64_t count;
+
+               VERIFY0(dsl_dir_hold_obj(dp, za->za_first_integer, NULL, FTAG,
+                   &chld_dd));
+
+               /*
+                * Ignore hidden ($FREE, $MOS & $ORIGIN) objsets and
+                * temporary datasets.
+                */
+               if (chld_dd->dd_myname[0] == '$' ||
+                   chld_dd->dd_myname[0] == '%') {
+                       dsl_dir_rele(chld_dd, FTAG);
+                       continue;
+               }
+
+               my_fs_cnt++;    /* count this child */
+
+               dsl_dir_init_fs_ss_count(chld_dd, tx);
+
+               VERIFY0(zap_lookup(os, chld_dd->dd_object,
+                   DD_FIELD_FILESYSTEM_COUNT, sizeof (count), 1, &count));
+               my_fs_cnt += count;
+               VERIFY0(zap_lookup(os, chld_dd->dd_object,
+                   DD_FIELD_SNAPSHOT_COUNT, sizeof (count), 1, &count));
+               my_ss_cnt += count;
+
+               dsl_dir_rele(chld_dd, FTAG);
+       }
+       zap_cursor_fini(zc);
+       /* Count my snapshots (we counted children's snapshots above) */
+       VERIFY0(dsl_dataset_hold_obj(dd->dd_pool,
+           dsl_dir_phys(dd)->dd_head_dataset_obj, FTAG, &ds));
+
+       for (zap_cursor_init(zc, os, dsl_dataset_phys(ds)->ds_snapnames_zapobj);
+           zap_cursor_retrieve(zc, za) == 0;
+           zap_cursor_advance(zc)) {
+               /* Don't count temporary snapshots */
+               if (za->za_name[0] != '%')
+                       my_ss_cnt++;
+       }
+       zap_cursor_fini(zc);
+
+       dsl_dataset_rele(ds, FTAG);
+
+       kmem_free(zc, sizeof (zap_cursor_t));
+       kmem_free(za, sizeof (zap_attribute_t));
+
+       /* we're in a sync task, update counts */
+       dmu_buf_will_dirty(dd->dd_dbuf, tx);
+       VERIFY0(zap_add(os, dd->dd_object, DD_FIELD_FILESYSTEM_COUNT,
+           sizeof (my_fs_cnt), 1, &my_fs_cnt, tx));
+       VERIFY0(zap_add(os, dd->dd_object, DD_FIELD_SNAPSHOT_COUNT,
+           sizeof (my_ss_cnt), 1, &my_ss_cnt, tx));
+}
+
+static int
+dsl_dir_actv_fs_ss_limit_check(void *arg, dmu_tx_t *tx)
+{
+       char *ddname = (char *)arg;
+       dsl_pool_t *dp = dmu_tx_pool(tx);
+       dsl_dataset_t *ds;
+       dsl_dir_t *dd;
+       int error;
+
+       error = dsl_dataset_hold(dp, ddname, FTAG, &ds);
+       if (error != 0)
+               return (error);
+
+       if (!spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_FS_SS_LIMIT)) {
+               dsl_dataset_rele(ds, FTAG);
+               return (SET_ERROR(ENOTSUP));
+       }
+
+       dd = ds->ds_dir;
+       if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_FS_SS_LIMIT) &&
+           dsl_dir_is_zapified(dd) &&
+           zap_contains(dp->dp_meta_objset, dd->dd_object,
+           DD_FIELD_FILESYSTEM_COUNT) == 0) {
+               dsl_dataset_rele(ds, FTAG);
+               return (SET_ERROR(EALREADY));
+       }
+
+       dsl_dataset_rele(ds, FTAG);
+       return (0);
+}
+
+static void
+dsl_dir_actv_fs_ss_limit_sync(void *arg, dmu_tx_t *tx)
+{
+       char *ddname = (char *)arg;
+       dsl_pool_t *dp = dmu_tx_pool(tx);
+       dsl_dataset_t *ds;
+       spa_t *spa;
+
+       VERIFY0(dsl_dataset_hold(dp, ddname, FTAG, &ds));
+
+       spa = dsl_dataset_get_spa(ds);
+
+       if (!spa_feature_is_active(spa, SPA_FEATURE_FS_SS_LIMIT)) {
+               /*
+                * Since the feature was not active and we're now setting a
+                * limit, increment the feature-active counter so that the
+                * feature becomes active for the first time.
+                *
+                * We are already in a sync task so we can update the MOS.
+                */
+               spa_feature_incr(spa, SPA_FEATURE_FS_SS_LIMIT, tx);
+       }
+
+       /*
+        * Since we are now setting a non-UINT64_MAX limit on the filesystem,
+        * we need to ensure the counts are correct. Descend down the tree from
+        * this point and update all of the counts to be accurate.
+        */
+       dsl_dir_init_fs_ss_count(ds->ds_dir, tx);
+
+       dsl_dataset_rele(ds, FTAG);
+}
+
+/*
+ * Make sure the feature is enabled and activate it if necessary.
+ * Since we're setting a limit, ensure the on-disk counts are valid.
+ * This is only called by the ioctl path when setting a limit value.
+ *
+ * We do not need to validate the new limit, since users who can change the
+ * limit are also allowed to exceed the limit.
+ */
+int
+dsl_dir_activate_fs_ss_limit(const char *ddname)
+{
+       int error;
+
+       error = dsl_sync_task(ddname, dsl_dir_actv_fs_ss_limit_check,
+           dsl_dir_actv_fs_ss_limit_sync, (void *)ddname, 0,
+           ZFS_SPACE_CHECK_RESERVED);
+
+       if (error == EALREADY)
+               error = 0;
+
+       return (error);
+}
+
+/*
+ * Used to determine if the filesystem_limit or snapshot_limit should be
+ * enforced. We allow the limit to be exceeded if the user has permission to
+ * write the property value. We pass in the creds that we got in the open
+ * context since we will always be the GZ root in syncing context. We also have
+ * to handle the case where we are allowed to change the limit on the current
+ * dataset, but there may be another limit in the tree above.
+ *
+ * We can never modify these two properties within a non-global zone. In
+ * addition, the other checks are modeled on zfs_secpolicy_write_perms. We
+ * can't use that function since we are already holding the dp_config_rwlock.
+ * In addition, we already have the dd and dealing with snapshots is simplified
+ * in this code.
+ */
+
+typedef enum {
+       ENFORCE_ALWAYS,
+       ENFORCE_NEVER,
+       ENFORCE_ABOVE
+} enforce_res_t;
+
+static enforce_res_t
+dsl_enforce_ds_ss_limits(dsl_dir_t *dd, zfs_prop_t prop, cred_t *cr)
+{
+       enforce_res_t enforce = ENFORCE_ALWAYS;
+       uint64_t obj;
+       dsl_dataset_t *ds;
+       uint64_t zoned;
+
+       ASSERT(prop == ZFS_PROP_FILESYSTEM_LIMIT ||
+           prop == ZFS_PROP_SNAPSHOT_LIMIT);
+
+#ifdef _KERNEL
+       if (crgetzoneid(cr) != GLOBAL_ZONEID)
+               return (ENFORCE_ALWAYS);
+
+       if (secpolicy_zfs(cr) == 0)
+               return (ENFORCE_NEVER);
+#endif
+
+       if ((obj = dsl_dir_phys(dd)->dd_head_dataset_obj) == 0)
+               return (ENFORCE_ALWAYS);
+
+       ASSERT(dsl_pool_config_held(dd->dd_pool));
+
+       if (dsl_dataset_hold_obj(dd->dd_pool, obj, FTAG, &ds) != 0)
+               return (ENFORCE_ALWAYS);
+
+       if (dsl_prop_get_ds(ds, "zoned", 8, 1, &zoned, NULL) || zoned) {
+               /* Only root can access zoned fs's from the GZ */
+               enforce = ENFORCE_ALWAYS;
+       } else {
+               if (dsl_deleg_access_impl(ds, zfs_prop_to_name(prop), cr) == 0)
+                       enforce = ENFORCE_ABOVE;
+       }
+
+       dsl_dataset_rele(ds, FTAG);
+       return (enforce);
+}
+
+/*
+ * Check if adding additional child filesystem(s) would exceed any filesystem
+ * limits or adding additional snapshot(s) would exceed any snapshot limits.
+ * The prop argument indicates which limit to check.
+ *
+ * Note that all filesystem limits up to the root (or the highest
+ * initialized) filesystem or the given ancestor must be satisfied.
+ */
+int
+dsl_fs_ss_limit_check(dsl_dir_t *dd, uint64_t delta, zfs_prop_t prop,
+    dsl_dir_t *ancestor, cred_t *cr)
+{
+       objset_t *os = dd->dd_pool->dp_meta_objset;
+       uint64_t limit, count;
+       char *count_prop;
+       enforce_res_t enforce;
+       int err = 0;
+
+       ASSERT(dsl_pool_config_held(dd->dd_pool));
+       ASSERT(prop == ZFS_PROP_FILESYSTEM_LIMIT ||
+           prop == ZFS_PROP_SNAPSHOT_LIMIT);
+
+       /*
+        * If we're allowed to change the limit, don't enforce the limit
+        * e.g. this can happen if a snapshot is taken by an administrative
+        * user in the global zone (i.e. a recursive snapshot by root).
+        * However, we must handle the case of delegated permissions where we
+        * are allowed to change the limit on the current dataset, but there
+        * is another limit in the tree above.
+        */
+       enforce = dsl_enforce_ds_ss_limits(dd, prop, cr);
+       if (enforce == ENFORCE_NEVER)
+               return (0);
+
+       /*
+        * e.g. if renaming a dataset with no snapshots, count adjustment
+        * is 0.
+        */
+       if (delta == 0)
+               return (0);
+
+       if (prop == ZFS_PROP_SNAPSHOT_LIMIT) {
+               /*
+                * We don't enforce the limit for temporary snapshots. This is
+                * indicated by a NULL cred_t argument.
+                */
+               if (cr == NULL)
+                       return (0);
+
+               count_prop = DD_FIELD_SNAPSHOT_COUNT;
+       } else {
+               count_prop = DD_FIELD_FILESYSTEM_COUNT;
+       }
+
+       /*
+        * If an ancestor has been provided, stop checking the limit once we
+        * hit that dir. We need this during rename so that we don't overcount
+        * the check once we recurse up to the common ancestor.
+        */
+       if (ancestor == dd)
+               return (0);
+
+       /*
+        * If we hit an uninitialized node while recursing up the tree, we can
+        * stop since we know there is no limit here (or above). The counts are
+        * not valid on this node and we know we won't touch this node's counts.
+        */
+       if (!dsl_dir_is_zapified(dd) || zap_lookup(os, dd->dd_object,
+           count_prop, sizeof (count), 1, &count) == ENOENT)
+               return (0);
+
+       err = dsl_prop_get_dd(dd, zfs_prop_to_name(prop), 8, 1, &limit, NULL,
+           B_FALSE);
+       if (err != 0)
+               return (err);
+
+       /* Is there a limit which we've hit? */
+       if (enforce == ENFORCE_ALWAYS && (count + delta) > limit)
+               return (SET_ERROR(EDQUOT));
+
+       if (dd->dd_parent != NULL)
+               err = dsl_fs_ss_limit_check(dd->dd_parent, delta, prop,
+                   ancestor, cr);
+
+       return (err);
+}
+
+/*
+ * Adjust the filesystem or snapshot count for the specified dsl_dir_t and all
+ * parents. When a new filesystem/snapshot is created, increment the count on
+ * all parents, and when a filesystem/snapshot is destroyed, decrement the
+ * count.
+ */
+void
+dsl_fs_ss_count_adjust(dsl_dir_t *dd, int64_t delta, const char *prop,
+    dmu_tx_t *tx)
+{
+       int err;
+       objset_t *os = dd->dd_pool->dp_meta_objset;
+       uint64_t count;
+
+       ASSERT(dsl_pool_config_held(dd->dd_pool));
+       ASSERT(dmu_tx_is_syncing(tx));
+       ASSERT(strcmp(prop, DD_FIELD_FILESYSTEM_COUNT) == 0 ||
+           strcmp(prop, DD_FIELD_SNAPSHOT_COUNT) == 0);
+
+       /*
+        * When we receive an incremental stream into a filesystem that already
+        * exists, a temporary clone is created.  We don't count this temporary
+        * clone, whose name begins with a '%'. We also ignore hidden ($FREE,
+        * $MOS & $ORIGIN) objsets.
+        */
+       if ((dd->dd_myname[0] == '%' || dd->dd_myname[0] == '$') &&
+           strcmp(prop, DD_FIELD_FILESYSTEM_COUNT) == 0)
+               return;
+
+       /*
+        * e.g. if renaming a dataset with no snapshots, count adjustment is 0
+        */
+       if (delta == 0)
+               return;
+
+       /*
+        * If we hit an uninitialized node while recursing up the tree, we can
+        * stop since we know the counts are not valid on this node and we
+        * know we shouldn't touch this node's counts. An uninitialized count
+        * on the node indicates that either the feature has not yet been
+        * activated or there are no limits on this part of the tree.
+        */
+       if (!dsl_dir_is_zapified(dd) || (err = zap_lookup(os, dd->dd_object,
+           prop, sizeof (count), 1, &count)) == ENOENT)
+               return;
+       VERIFY0(err);
+
+       count += delta;
+       /* Use a signed verify to make sure we're not neg. */
+       VERIFY3S(count, >=, 0);
+
+       VERIFY0(zap_update(os, dd->dd_object, prop, sizeof (count), 1, &count,
+           tx));
+
+       /* Roll up this additional count into our ancestors */
+       if (dd->dd_parent != NULL)
+               dsl_fs_ss_count_adjust(dd->dd_parent, delta, prop, tx);
+}
+
+uint64_t
+dsl_dir_create_sync(dsl_pool_t *dp, dsl_dir_t *pds, const char *name,
+    dmu_tx_t *tx)
+{
+       objset_t *mos = dp->dp_meta_objset;
+       uint64_t ddobj;
+       dsl_dir_phys_t *ddphys;
+       dmu_buf_t *dbuf;
+
+       ddobj = dmu_object_alloc(mos, DMU_OT_DSL_DIR, 0,
+           DMU_OT_DSL_DIR, sizeof (dsl_dir_phys_t), tx);
+       if (pds) {
+               VERIFY(0 == zap_add(mos, dsl_dir_phys(pds)->dd_child_dir_zapobj,
+                   name, sizeof (uint64_t), 1, &ddobj, tx));
+       } else {
+               /* it's the root dir */
+               VERIFY(0 == zap_add(mos, DMU_POOL_DIRECTORY_OBJECT,
+                   DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1, &ddobj, tx));
+       }
+       VERIFY(0 == dmu_bonus_hold(mos, ddobj, FTAG, &dbuf));
+       dmu_buf_will_dirty(dbuf, tx);
+       ddphys = dbuf->db_data;
+
+       ddphys->dd_creation_time = gethrestime_sec();
+       if (pds) {
+               ddphys->dd_parent_obj = pds->dd_object;
+
+               /* update the filesystem counts */
+               dsl_fs_ss_count_adjust(pds, 1, DD_FIELD_FILESYSTEM_COUNT, tx);
+       }
+       ddphys->dd_props_zapobj = zap_create(mos,
+           DMU_OT_DSL_PROPS, DMU_OT_NONE, 0, tx);
+       ddphys->dd_child_dir_zapobj = zap_create(mos,
+           DMU_OT_DSL_DIR_CHILD_MAP, DMU_OT_NONE, 0, tx);
+       if (spa_version(dp->dp_spa) >= SPA_VERSION_USED_BREAKDOWN)
+               ddphys->dd_flags |= DD_FLAG_USED_BREAKDOWN;
+       dmu_buf_rele(dbuf, FTAG);
+
+       return (ddobj);
+}
+
+boolean_t
+dsl_dir_is_clone(dsl_dir_t *dd)
+{
+       return (dsl_dir_phys(dd)->dd_origin_obj &&
+           (dd->dd_pool->dp_origin_snap == NULL ||
+           dsl_dir_phys(dd)->dd_origin_obj !=
+           dd->dd_pool->dp_origin_snap->ds_object));
+}
+
+void
+dsl_dir_stats(dsl_dir_t *dd, nvlist_t *nv)
+{
+       mutex_enter(&dd->dd_lock);
+       dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USED,
+           dsl_dir_phys(dd)->dd_used_bytes);
+       dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_QUOTA,
+           dsl_dir_phys(dd)->dd_quota);
+       dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_RESERVATION,
+           dsl_dir_phys(dd)->dd_reserved);
+       dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_COMPRESSRATIO,
+           dsl_dir_phys(dd)->dd_compressed_bytes == 0 ? 100 :
+           (dsl_dir_phys(dd)->dd_uncompressed_bytes * 100 /
+           dsl_dir_phys(dd)->dd_compressed_bytes));
+       dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_LOGICALUSED,
+           dsl_dir_phys(dd)->dd_uncompressed_bytes);
+       if (dsl_dir_phys(dd)->dd_flags & DD_FLAG_USED_BREAKDOWN) {
+               dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDSNAP,
+                   dsl_dir_phys(dd)->dd_used_breakdown[DD_USED_SNAP]);
+               dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDDS,
+                   dsl_dir_phys(dd)->dd_used_breakdown[DD_USED_HEAD]);
+               dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDREFRESERV,
+                   dsl_dir_phys(dd)->dd_used_breakdown[DD_USED_REFRSRV]);
+               dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDCHILD,
+                   dsl_dir_phys(dd)->dd_used_breakdown[DD_USED_CHILD] +
+                   dsl_dir_phys(dd)->dd_used_breakdown[DD_USED_CHILD_RSRV]);
+       }
+       mutex_exit(&dd->dd_lock);
+
+       if (dsl_dir_is_zapified(dd)) {
+               uint64_t count;
+               objset_t *os = dd->dd_pool->dp_meta_objset;
+
+               if (zap_lookup(os, dd->dd_object, DD_FIELD_FILESYSTEM_COUNT,
+                   sizeof (count), 1, &count) == 0) {
+                       dsl_prop_nvlist_add_uint64(nv,
+                           ZFS_PROP_FILESYSTEM_COUNT, count);
+               }
+               if (zap_lookup(os, dd->dd_object, DD_FIELD_SNAPSHOT_COUNT,
+                   sizeof (count), 1, &count) == 0) {
+                       dsl_prop_nvlist_add_uint64(nv,
+                           ZFS_PROP_SNAPSHOT_COUNT, count);
+               }
+       }
+
+       if (dsl_dir_is_clone(dd)) {
+               dsl_dataset_t *ds;
+               char buf[MAXNAMELEN];
+
+               VERIFY0(dsl_dataset_hold_obj(dd->dd_pool,
+                   dsl_dir_phys(dd)->dd_origin_obj, FTAG, &ds));
+               dsl_dataset_name(ds, buf);
+               dsl_dataset_rele(ds, FTAG);
+               dsl_prop_nvlist_add_string(nv, ZFS_PROP_ORIGIN, buf);
+       }
+}
+
+void
+dsl_dir_dirty(dsl_dir_t *dd, dmu_tx_t *tx)
+{
+       dsl_pool_t *dp = dd->dd_pool;
+
+       ASSERT(dsl_dir_phys(dd));
+
+       if (txg_list_add(&dp->dp_dirty_dirs, dd, tx->tx_txg)) {
+               /* up the hold count until we can be written out */
+               dmu_buf_add_ref(dd->dd_dbuf, dd);
+       }
+}
+
+static int64_t
+parent_delta(dsl_dir_t *dd, uint64_t used, int64_t delta)
+{
+       uint64_t old_accounted = MAX(used, dsl_dir_phys(dd)->dd_reserved);
+       uint64_t new_accounted =
+           MAX(used + delta, dsl_dir_phys(dd)->dd_reserved);
+       return (new_accounted - old_accounted);
+}
+
+void
+dsl_dir_sync(dsl_dir_t *dd, dmu_tx_t *tx)
+{
+       ASSERT(dmu_tx_is_syncing(tx));
+
+       mutex_enter(&dd->dd_lock);
+       ASSERT0(dd->dd_tempreserved[tx->tx_txg&TXG_MASK]);
+       dprintf_dd(dd, "txg=%llu towrite=%lluK\n", tx->tx_txg,
+           dd->dd_space_towrite[tx->tx_txg&TXG_MASK] / 1024);
+       dd->dd_space_towrite[tx->tx_txg&TXG_MASK] = 0;
+       mutex_exit(&dd->dd_lock);
+
+       /* release the hold from dsl_dir_dirty */
+       dmu_buf_rele(dd->dd_dbuf, dd);
+}
+
+static uint64_t
+dsl_dir_space_towrite(dsl_dir_t *dd)
+{
+       uint64_t space = 0;
+       int i;
+
+       ASSERT(MUTEX_HELD(&dd->dd_lock));
+
+       for (i = 0; i < TXG_SIZE; i++) {
+               space += dd->dd_space_towrite[i&TXG_MASK];
+               ASSERT3U(dd->dd_space_towrite[i&TXG_MASK], >=, 0);
+       }
+       return (space);
+}
+
+/*
+ * How much space would dd have available if ancestor had delta applied
+ * to it?  If ondiskonly is set, we're only interested in what's
+ * on-disk, not estimated pending changes.
+ */
+uint64_t
+dsl_dir_space_available(dsl_dir_t *dd,
+    dsl_dir_t *ancestor, int64_t delta, int ondiskonly)
+{
+       uint64_t parentspace, myspace, quota, used;
+
+       /*
+        * If there are no restrictions otherwise, assume we have
+        * unlimited space available.
+        */
+       quota = UINT64_MAX;
+       parentspace = UINT64_MAX;
+
+       if (dd->dd_parent != NULL) {
+               parentspace = dsl_dir_space_available(dd->dd_parent,
+                   ancestor, delta, ondiskonly);
+       }
+
+       mutex_enter(&dd->dd_lock);
+       if (dsl_dir_phys(dd)->dd_quota != 0)
+               quota = dsl_dir_phys(dd)->dd_quota;
+       used = dsl_dir_phys(dd)->dd_used_bytes;
+       if (!ondiskonly)
+               used += dsl_dir_space_towrite(dd);
+
+       if (dd->dd_parent == NULL) {
+               uint64_t poolsize = dsl_pool_adjustedsize(dd->dd_pool, FALSE);
+               quota = MIN(quota, poolsize);
+       }
+
+       if (dsl_dir_phys(dd)->dd_reserved > used && parentspace != UINT64_MAX) {
+               /*
+                * We have some space reserved, in addition to what our
+                * parent gave us.
+                */
+               parentspace += dsl_dir_phys(dd)->dd_reserved - used;
+       }
+
+       if (dd == ancestor) {
+               ASSERT(delta <= 0);
+               ASSERT(used >= -delta);
+               used += delta;
+               if (parentspace != UINT64_MAX)
+                       parentspace -= delta;
+       }
+
+       if (used > quota) {
+               /* over quota */
+               myspace = 0;
+       } else {
+               /*
+                * the lesser of the space provided by our parent and
+                * the space left in our quota
+                */
+               myspace = MIN(parentspace, quota - used);
+       }
+
+       mutex_exit(&dd->dd_lock);
+
+       return (myspace);
+}
+
+struct tempreserve {
+       list_node_t tr_node;
+       dsl_dir_t *tr_ds;
+       uint64_t tr_size;
+};
+
+static int
+dsl_dir_tempreserve_impl(dsl_dir_t *dd, uint64_t asize, boolean_t netfree,
+    boolean_t ignorequota, boolean_t checkrefquota, list_t *tr_list,
+    dmu_tx_t *tx, boolean_t first)
+{
+       uint64_t txg = tx->tx_txg;
+       uint64_t est_inflight, used_on_disk, quota, parent_rsrv;
+       uint64_t deferred = 0;
+       struct tempreserve *tr;
+       int retval = EDQUOT;
+       int txgidx = txg & TXG_MASK;
+       int i;
+       uint64_t ref_rsrv = 0;
+
+       ASSERT3U(txg, !=, 0);
+       ASSERT3S(asize, >, 0);
+
+       mutex_enter(&dd->dd_lock);
+
+       /*
+        * Check against the dsl_dir's quota.  We don't add in the delta
+        * when checking for over-quota because they get one free hit.
+        */
+       est_inflight = dsl_dir_space_towrite(dd);
+       for (i = 0; i < TXG_SIZE; i++)
+               est_inflight += dd->dd_tempreserved[i];
+       used_on_disk = dsl_dir_phys(dd)->dd_used_bytes;
+
+       /*
+        * On the first iteration, fetch the dataset's used-on-disk and
+        * refreservation values. Also, if checkrefquota is set, test if
+        * allocating this space would exceed the dataset's refquota.
+        */
+       if (first && tx->tx_objset) {
+               int error;
+               dsl_dataset_t *ds = tx->tx_objset->os_dsl_dataset;
+
+               error = dsl_dataset_check_quota(ds, checkrefquota,
+                   asize, est_inflight, &used_on_disk, &ref_rsrv);
+               if (error) {
+                       mutex_exit(&dd->dd_lock);
+                       DMU_TX_STAT_BUMP(dmu_tx_quota);
+                       return (error);
+               }
+       }
+
+       /*
+        * If this transaction will result in a net free of space,
+        * we want to let it through.
+        */
+       if (ignorequota || netfree || dsl_dir_phys(dd)->dd_quota == 0)
+               quota = UINT64_MAX;
+       else
+               quota = dsl_dir_phys(dd)->dd_quota;
+
+       /*
+        * Adjust the quota against the actual pool size at the root
+        * minus any outstanding deferred frees.
+        * To ensure that it's possible to remove files from a full
+        * pool without inducing transient overcommits, we throttle
+        * netfree transactions against a quota that is slightly larger,
+        * but still within the pool's allocation slop.  In cases where
+        * we're very close to full, this will allow a steady trickle of
+        * removes to get through.
+        */
+       if (dd->dd_parent == NULL) {
+               spa_t *spa = dd->dd_pool->dp_spa;
+               uint64_t poolsize = dsl_pool_adjustedsize(dd->dd_pool, netfree);
+               deferred = metaslab_class_get_deferred(spa_normal_class(spa));
+               if (poolsize - deferred < quota) {
+                       quota = poolsize - deferred;
+                       retval = ENOSPC;
+               }
+       }
+
+       /*
+        * If they are requesting more space, and our current estimate
+        * is over quota, they get to try again unless the actual
+        * on-disk is over quota and there are no pending changes (which
+        * may free up space for us).
+        */
+       if (used_on_disk + est_inflight >= quota) {
+               if (est_inflight > 0 || used_on_disk < quota ||
+                   (retval == ENOSPC && used_on_disk < quota + deferred))
+                       retval = ERESTART;
+               dprintf_dd(dd, "failing: used=%lluK inflight = %lluK "
+                   "quota=%lluK tr=%lluK err=%d\n",
+                   used_on_disk>>10, est_inflight>>10,
+                   quota>>10, asize>>10, retval);
+               mutex_exit(&dd->dd_lock);
+               DMU_TX_STAT_BUMP(dmu_tx_quota);
+               return (SET_ERROR(retval));
+       }
+
+       /* We need to up our estimated delta before dropping dd_lock */
+       dd->dd_tempreserved[txgidx] += asize;
+
+       parent_rsrv = parent_delta(dd, used_on_disk + est_inflight,
+           asize - ref_rsrv);
+       mutex_exit(&dd->dd_lock);
+
+       tr = kmem_zalloc(sizeof (struct tempreserve), KM_SLEEP);
+       tr->tr_ds = dd;
+       tr->tr_size = asize;
+       list_insert_tail(tr_list, tr);
+
+       /* see if it's OK with our parent */
+       if (dd->dd_parent && parent_rsrv) {
+               boolean_t ismos = (dsl_dir_phys(dd)->dd_head_dataset_obj == 0);
+
+               return (dsl_dir_tempreserve_impl(dd->dd_parent,
+                   parent_rsrv, netfree, ismos, TRUE, tr_list, tx, FALSE));
+       } else {
+               return (0);
+       }
+}
+
+/*
+ * Reserve space in this dsl_dir, to be used in this tx's txg.
+ * After the space has been dirtied (and dsl_dir_willuse_space()
+ * has been called), the reservation should be canceled, using
+ * dsl_dir_tempreserve_clear().
+ */
+int
+dsl_dir_tempreserve_space(dsl_dir_t *dd, uint64_t lsize, uint64_t asize,
+    uint64_t fsize, uint64_t usize, void **tr_cookiep, dmu_tx_t *tx)
+{
+       int err;
+       list_t *tr_list;
+
+       if (asize == 0) {
+               *tr_cookiep = NULL;
+               return (0);
+       }
+
+       tr_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
+       list_create(tr_list, sizeof (struct tempreserve),
+           offsetof(struct tempreserve, tr_node));
+       ASSERT3S(asize, >, 0);
+       ASSERT3S(fsize, >=, 0);
+
+       err = arc_tempreserve_space(lsize, tx->tx_txg);
+       if (err == 0) {
+               struct tempreserve *tr;
+
+               tr = kmem_zalloc(sizeof (struct tempreserve), KM_SLEEP);
+               tr->tr_size = lsize;
+               list_insert_tail(tr_list, tr);
+       } else {
+               if (err == EAGAIN) {
+                       /*
+                        * If arc_memory_throttle() detected that pageout
+                        * is running and we are low on memory, we delay new
+                        * non-pageout transactions to give pageout an
+                        * advantage.
+                        *
+                        * It is unfortunate to be delaying while the caller's
+                        * locks are held.
+                        */
+                       txg_delay(dd->dd_pool, tx->tx_txg,
+                           MSEC2NSEC(10), MSEC2NSEC(10));
+                       err = SET_ERROR(ERESTART);
+               }
+       }
+
+       if (err == 0) {
+               err = dsl_dir_tempreserve_impl(dd, asize, fsize >= asize,
+                   FALSE, asize > usize, tr_list, tx, TRUE);
+       }
+
+       if (err != 0)
+               dsl_dir_tempreserve_clear(tr_list, tx);
+       else
+               *tr_cookiep = tr_list;
+
+       return (err);
+}
+
+/*
+ * Clear a temporary reservation that we previously made with
+ * dsl_dir_tempreserve_space().
+ */
+void
+dsl_dir_tempreserve_clear(void *tr_cookie, dmu_tx_t *tx)
+{
+       int txgidx = tx->tx_txg & TXG_MASK;
+       list_t *tr_list = tr_cookie;
+       struct tempreserve *tr;
+
+       ASSERT3U(tx->tx_txg, !=, 0);
+
+       if (tr_cookie == NULL)
+               return;
+
+       while ((tr = list_head(tr_list)) != NULL) {
+               if (tr->tr_ds) {
+                       mutex_enter(&tr->tr_ds->dd_lock);
+                       ASSERT3U(tr->tr_ds->dd_tempreserved[txgidx], >=,
+                           tr->tr_size);
+                       tr->tr_ds->dd_tempreserved[txgidx] -= tr->tr_size;
+                       mutex_exit(&tr->tr_ds->dd_lock);
+               } else {
+                       arc_tempreserve_clear(tr->tr_size);
+               }
+               list_remove(tr_list, tr);
+               kmem_free(tr, sizeof (struct tempreserve));
+       }
+
+       kmem_free(tr_list, sizeof (list_t));
+}
+
+/*
+ * This should be called from open context when we think we're going to write
+ * or free space, for example when dirtying data. Be conservative; it's okay
+ * to write less space or free more, but we don't want to write more or free
+ * less than the amount specified.
+ *
+ * NOTE: The behavior of this function is identical to the Illumos / FreeBSD
+ * version however it has been adjusted to use an iterative rather then
+ * recursive algorithm to minimize stack usage.
+ */
+void
+dsl_dir_willuse_space(dsl_dir_t *dd, int64_t space, dmu_tx_t *tx)
+{
+       int64_t parent_space;
+       uint64_t est_used;
+
+       do {
+               mutex_enter(&dd->dd_lock);
+               if (space > 0)
+                       dd->dd_space_towrite[tx->tx_txg & TXG_MASK] += space;
+
+               est_used = dsl_dir_space_towrite(dd) +
+                   dsl_dir_phys(dd)->dd_used_bytes;
+               parent_space = parent_delta(dd, est_used, space);
+               mutex_exit(&dd->dd_lock);
+
+               /* Make sure that we clean up dd_space_to* */
+               dsl_dir_dirty(dd, tx);
+
+               dd = dd->dd_parent;
+               space = parent_space;
+       } while (space && dd);
+}
+
+/* call from syncing context when we actually write/free space for this dd */
+void
+dsl_dir_diduse_space(dsl_dir_t *dd, dd_used_t type,
+    int64_t used, int64_t compressed, int64_t uncompressed, dmu_tx_t *tx)
+{
+       int64_t accounted_delta;
+
+       /*
+        * dsl_dataset_set_refreservation_sync_impl() calls this with
+        * dd_lock held, so that it can atomically update
+        * ds->ds_reserved and the dsl_dir accounting, so that
+        * dsl_dataset_check_quota() can see dataset and dir accounting
+        * consistently.
+        */
+       boolean_t needlock = !MUTEX_HELD(&dd->dd_lock);
+
+       ASSERT(dmu_tx_is_syncing(tx));
+       ASSERT(type < DD_USED_NUM);
+
+       dmu_buf_will_dirty(dd->dd_dbuf, tx);
+
+       if (needlock)
+               mutex_enter(&dd->dd_lock);
+       accounted_delta =
+           parent_delta(dd, dsl_dir_phys(dd)->dd_used_bytes, used);
+       ASSERT(used >= 0 || dsl_dir_phys(dd)->dd_used_bytes >= -used);
+       ASSERT(compressed >= 0 ||
+           dsl_dir_phys(dd)->dd_compressed_bytes >= -compressed);
+       ASSERT(uncompressed >= 0 ||
+           dsl_dir_phys(dd)->dd_uncompressed_bytes >= -uncompressed);
+       dsl_dir_phys(dd)->dd_used_bytes += used;
+       dsl_dir_phys(dd)->dd_uncompressed_bytes += uncompressed;
+       dsl_dir_phys(dd)->dd_compressed_bytes += compressed;
+
+       if (dsl_dir_phys(dd)->dd_flags & DD_FLAG_USED_BREAKDOWN) {
+               ASSERT(used > 0 ||
+                   dsl_dir_phys(dd)->dd_used_breakdown[type] >= -used);
+               dsl_dir_phys(dd)->dd_used_breakdown[type] += used;
+#ifdef DEBUG
+               {
+                       dd_used_t t;
+                       uint64_t u = 0;
+                       for (t = 0; t < DD_USED_NUM; t++)
+                               u += dsl_dir_phys(dd)->dd_used_breakdown[t];
+                       ASSERT3U(u, ==, dsl_dir_phys(dd)->dd_used_bytes);
+               }
+#endif
+       }
+       if (needlock)
+               mutex_exit(&dd->dd_lock);
+
+       if (dd->dd_parent != NULL) {
+               dsl_dir_diduse_space(dd->dd_parent, DD_USED_CHILD,
+                   accounted_delta, compressed, uncompressed, tx);
+               dsl_dir_transfer_space(dd->dd_parent,
+                   used - accounted_delta,
+                   DD_USED_CHILD_RSRV, DD_USED_CHILD, tx);
+       }
+}
+
+void
+dsl_dir_transfer_space(dsl_dir_t *dd, int64_t delta,
+    dd_used_t oldtype, dd_used_t newtype, dmu_tx_t *tx)
+{
+       ASSERT(dmu_tx_is_syncing(tx));
+       ASSERT(oldtype < DD_USED_NUM);
+       ASSERT(newtype < DD_USED_NUM);
+
+       if (delta == 0 ||
+           !(dsl_dir_phys(dd)->dd_flags & DD_FLAG_USED_BREAKDOWN))
+               return;
+
+       dmu_buf_will_dirty(dd->dd_dbuf, tx);
+       mutex_enter(&dd->dd_lock);
+       ASSERT(delta > 0 ?
+           dsl_dir_phys(dd)->dd_used_breakdown[oldtype] >= delta :
+           dsl_dir_phys(dd)->dd_used_breakdown[newtype] >= -delta);
+       ASSERT(dsl_dir_phys(dd)->dd_used_bytes >= ABS(delta));
+       dsl_dir_phys(dd)->dd_used_breakdown[oldtype] -= delta;
+       dsl_dir_phys(dd)->dd_used_breakdown[newtype] += delta;
+       mutex_exit(&dd->dd_lock);
+}
+
+typedef struct dsl_dir_set_qr_arg {
+       const char *ddsqra_name;
+       zprop_source_t ddsqra_source;
+       uint64_t ddsqra_value;
+} dsl_dir_set_qr_arg_t;
+
+static int
+dsl_dir_set_quota_check(void *arg, dmu_tx_t *tx)
+{
+       dsl_dir_set_qr_arg_t *ddsqra = arg;
+       dsl_pool_t *dp = dmu_tx_pool(tx);
+       dsl_dataset_t *ds;
+       int error;
+       uint64_t towrite, newval;
+
+       error = dsl_dataset_hold(dp, ddsqra->ddsqra_name, FTAG, &ds);
+       if (error != 0)
+               return (error);
+
+       error = dsl_prop_predict(ds->ds_dir, "quota",
+           ddsqra->ddsqra_source, ddsqra->ddsqra_value, &newval);
+       if (error != 0) {
+               dsl_dataset_rele(ds, FTAG);
+               return (error);
+       }
+
+       if (newval == 0) {
+               dsl_dataset_rele(ds, FTAG);
+               return (0);
+       }
+
+       mutex_enter(&ds->ds_dir->dd_lock);
+       /*
+        * If we are doing the preliminary check in open context, and
+        * there are pending changes, then don't fail it, since the
+        * pending changes could under-estimate the amount of space to be
+        * freed up.
+        */
+       towrite = dsl_dir_space_towrite(ds->ds_dir);
+       if ((dmu_tx_is_syncing(tx) || towrite == 0) &&
+           (newval < dsl_dir_phys(ds->ds_dir)->dd_reserved ||
+           newval < dsl_dir_phys(ds->ds_dir)->dd_used_bytes + towrite)) {
+               error = SET_ERROR(ENOSPC);
+       }
+       mutex_exit(&ds->ds_dir->dd_lock);
+       dsl_dataset_rele(ds, FTAG);
+       return (error);
+}
+
+static void
+dsl_dir_set_quota_sync(void *arg, dmu_tx_t *tx)
+{
+       dsl_dir_set_qr_arg_t *ddsqra = arg;
+       dsl_pool_t *dp = dmu_tx_pool(tx);
+       dsl_dataset_t *ds;
+       uint64_t newval;
+
+       VERIFY0(dsl_dataset_hold(dp, ddsqra->ddsqra_name, FTAG, &ds));
+
+       if (spa_version(dp->dp_spa) >= SPA_VERSION_RECVD_PROPS) {
+               dsl_prop_set_sync_impl(ds, zfs_prop_to_name(ZFS_PROP_QUOTA),
+                   ddsqra->ddsqra_source, sizeof (ddsqra->ddsqra_value), 1,
+                   &ddsqra->ddsqra_value, tx);
+
+               VERIFY0(dsl_prop_get_int_ds(ds,
+                   zfs_prop_to_name(ZFS_PROP_QUOTA), &newval));
+       } else {
+               newval = ddsqra->ddsqra_value;
+               spa_history_log_internal_ds(ds, "set", tx, "%s=%lld",
+                   zfs_prop_to_name(ZFS_PROP_QUOTA), (longlong_t)newval);
+       }
+
+       dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
+       mutex_enter(&ds->ds_dir->dd_lock);
+       dsl_dir_phys(ds->ds_dir)->dd_quota = newval;
+       mutex_exit(&ds->ds_dir->dd_lock);
+       dsl_dataset_rele(ds, FTAG);
+}
+
+int
+dsl_dir_set_quota(const char *ddname, zprop_source_t source, uint64_t quota)
+{
+       dsl_dir_set_qr_arg_t ddsqra;
+
+       ddsqra.ddsqra_name = ddname;
+       ddsqra.ddsqra_source = source;
+       ddsqra.ddsqra_value = quota;
+
+       return (dsl_sync_task(ddname, dsl_dir_set_quota_check,
+           dsl_dir_set_quota_sync, &ddsqra, 0, ZFS_SPACE_CHECK_NONE));
+}
+
+int
+dsl_dir_set_reservation_check(void *arg, dmu_tx_t *tx)
+{
+       dsl_dir_set_qr_arg_t *ddsqra = arg;
+       dsl_pool_t *dp = dmu_tx_pool(tx);
+       dsl_dataset_t *ds;
+       dsl_dir_t *dd;
+       uint64_t newval, used, avail;
+       int error;
+
+       error = dsl_dataset_hold(dp, ddsqra->ddsqra_name, FTAG, &ds);
+       if (error != 0)
+               return (error);
+       dd = ds->ds_dir;
+
+       /*
+        * If we are doing the preliminary check in open context, the
+        * space estimates may be inaccurate.
+        */
+       if (!dmu_tx_is_syncing(tx)) {
+               dsl_dataset_rele(ds, FTAG);
+               return (0);
+       }
+
+       error = dsl_prop_predict(ds->ds_dir,
+           zfs_prop_to_name(ZFS_PROP_RESERVATION),
+           ddsqra->ddsqra_source, ddsqra->ddsqra_value, &newval);
+       if (error != 0) {
+               dsl_dataset_rele(ds, FTAG);
+               return (error);
+       }
+
+       mutex_enter(&dd->dd_lock);
+       used = dsl_dir_phys(dd)->dd_used_bytes;
+       mutex_exit(&dd->dd_lock);
+
+       if (dd->dd_parent) {
+               avail = dsl_dir_space_available(dd->dd_parent,
+                   NULL, 0, FALSE);
+       } else {
+               avail = dsl_pool_adjustedsize(dd->dd_pool, B_FALSE) - used;
+       }
+
+       if (MAX(used, newval) > MAX(used, dsl_dir_phys(dd)->dd_reserved)) {
+               uint64_t delta = MAX(used, newval) -
+                   MAX(used, dsl_dir_phys(dd)->dd_reserved);
+
+               if (delta > avail ||
+                   (dsl_dir_phys(dd)->dd_quota > 0 &&
+                   newval > dsl_dir_phys(dd)->dd_quota))
+                       error = SET_ERROR(ENOSPC);
+       }
+
+       dsl_dataset_rele(ds, FTAG);
+       return (error);
+}
+
+void
+dsl_dir_set_reservation_sync_impl(dsl_dir_t *dd, uint64_t value, dmu_tx_t *tx)
+{
+       uint64_t used;
+       int64_t delta;
+
+       dmu_buf_will_dirty(dd->dd_dbuf, tx);
+
+       mutex_enter(&dd->dd_lock);
+       used = dsl_dir_phys(dd)->dd_used_bytes;
+       delta = MAX(used, value) - MAX(used, dsl_dir_phys(dd)->dd_reserved);
+       dsl_dir_phys(dd)->dd_reserved = value;
+
+       if (dd->dd_parent != NULL) {
+               /* Roll up this additional usage into our ancestors */
+               dsl_dir_diduse_space(dd->dd_parent, DD_USED_CHILD_RSRV,
+                   delta, 0, 0, tx);
+       }
+       mutex_exit(&dd->dd_lock);
+}
+
+static void
+dsl_dir_set_reservation_sync(void *arg, dmu_tx_t *tx)
+{
+       dsl_dir_set_qr_arg_t *ddsqra = arg;
+       dsl_pool_t *dp = dmu_tx_pool(tx);
+       dsl_dataset_t *ds;
+       uint64_t newval;
+
+       VERIFY0(dsl_dataset_hold(dp, ddsqra->ddsqra_name, FTAG, &ds));
+
+       if (spa_version(dp->dp_spa) >= SPA_VERSION_RECVD_PROPS) {
+               dsl_prop_set_sync_impl(ds,
+                   zfs_prop_to_name(ZFS_PROP_RESERVATION),
+                   ddsqra->ddsqra_source, sizeof (ddsqra->ddsqra_value), 1,
+                   &ddsqra->ddsqra_value, tx);
+
+               VERIFY0(dsl_prop_get_int_ds(ds,
+                   zfs_prop_to_name(ZFS_PROP_RESERVATION), &newval));
+       } else {
+               newval = ddsqra->ddsqra_value;
+               spa_history_log_internal_ds(ds, "set", tx, "%s=%lld",
+                   zfs_prop_to_name(ZFS_PROP_RESERVATION),
+                   (longlong_t)newval);
+       }
+
+       dsl_dir_set_reservation_sync_impl(ds->ds_dir, newval, tx);
+       dsl_dataset_rele(ds, FTAG);
+}
+
+int
+dsl_dir_set_reservation(const char *ddname, zprop_source_t source,
+    uint64_t reservation)
+{
+       dsl_dir_set_qr_arg_t ddsqra;
+
+       ddsqra.ddsqra_name = ddname;
+       ddsqra.ddsqra_source = source;
+       ddsqra.ddsqra_value = reservation;
+
+       return (dsl_sync_task(ddname, dsl_dir_set_reservation_check,
+           dsl_dir_set_reservation_sync, &ddsqra, 0, ZFS_SPACE_CHECK_NONE));
+}
+
+static dsl_dir_t *
+closest_common_ancestor(dsl_dir_t *ds1, dsl_dir_t *ds2)
+{
+       for (; ds1; ds1 = ds1->dd_parent) {
+               dsl_dir_t *dd;
+               for (dd = ds2; dd; dd = dd->dd_parent) {
+                       if (ds1 == dd)
+                               return (dd);
+               }
+       }
+       return (NULL);
+}
+
+/*
+ * If delta is applied to dd, how much of that delta would be applied to
+ * ancestor?  Syncing context only.
+ */
+static int64_t
+would_change(dsl_dir_t *dd, int64_t delta, dsl_dir_t *ancestor)
+{
+       if (dd == ancestor)
+               return (delta);
+
+       mutex_enter(&dd->dd_lock);
+       delta = parent_delta(dd, dsl_dir_phys(dd)->dd_used_bytes, delta);
+       mutex_exit(&dd->dd_lock);
+       return (would_change(dd->dd_parent, delta, ancestor));
+}
+
+typedef struct dsl_dir_rename_arg {
+       const char *ddra_oldname;
+       const char *ddra_newname;
+       cred_t *ddra_cred;
+} dsl_dir_rename_arg_t;
+
+/* ARGSUSED */
+static int
+dsl_valid_rename(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
+{
+       int *deltap = arg;
+       char namebuf[MAXNAMELEN];
+
+       dsl_dataset_name(ds, namebuf);
+
+       if (strlen(namebuf) + *deltap >= MAXNAMELEN)
+               return (SET_ERROR(ENAMETOOLONG));
+       return (0);
+}
+
+static int
+dsl_dir_rename_check(void *arg, dmu_tx_t *tx)
+{
+       dsl_dir_rename_arg_t *ddra = arg;
+       dsl_pool_t *dp = dmu_tx_pool(tx);
+       dsl_dir_t *dd, *newparent;
+       const char *mynewname;
+       int error;
+       int delta = strlen(ddra->ddra_newname) - strlen(ddra->ddra_oldname);
+
+       /* target dir should exist */
+       error = dsl_dir_hold(dp, ddra->ddra_oldname, FTAG, &dd, NULL);
+       if (error != 0)
+               return (error);
+
+       /* new parent should exist */
+       error = dsl_dir_hold(dp, ddra->ddra_newname, FTAG,
+           &newparent, &mynewname);
+       if (error != 0) {
+               dsl_dir_rele(dd, FTAG);
+               return (error);
+       }
+
+       /* can't rename to different pool */
+       if (dd->dd_pool != newparent->dd_pool) {
+               dsl_dir_rele(newparent, FTAG);
+               dsl_dir_rele(dd, FTAG);
+               return (SET_ERROR(EXDEV));
+       }
+
+       /* new name should not already exist */
+       if (mynewname == NULL) {
+               dsl_dir_rele(newparent, FTAG);
+               dsl_dir_rele(dd, FTAG);
+               return (SET_ERROR(EEXIST));
+       }
+
+       /* if the name length is growing, validate child name lengths */
+       if (delta > 0) {
+               error = dmu_objset_find_dp(dp, dd->dd_object, dsl_valid_rename,
+                   &delta, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
+               if (error != 0) {
+                       dsl_dir_rele(newparent, FTAG);
+                       dsl_dir_rele(dd, FTAG);
+                       return (error);
+               }
+       }
+
+       if (dmu_tx_is_syncing(tx)) {
+               if (spa_feature_is_active(dp->dp_spa,
+                   SPA_FEATURE_FS_SS_LIMIT)) {
+                       /*
+                        * Although this is the check function and we don't
+                        * normally make on-disk changes in check functions,
+                        * we need to do that here.
+                        *
+                        * Ensure this portion of the tree's counts have been
+                        * initialized in case the new parent has limits set.
+                        */
+                       dsl_dir_init_fs_ss_count(dd, tx);
+               }
+       }
+
+       if (newparent != dd->dd_parent) {
+               /* is there enough space? */
+               uint64_t myspace =
+                   MAX(dsl_dir_phys(dd)->dd_used_bytes,
+                   dsl_dir_phys(dd)->dd_reserved);
+               objset_t *os = dd->dd_pool->dp_meta_objset;
+               uint64_t fs_cnt = 0;
+               uint64_t ss_cnt = 0;
+
+               if (dsl_dir_is_zapified(dd)) {
+                       int err;
+
+                       err = zap_lookup(os, dd->dd_object,
+                           DD_FIELD_FILESYSTEM_COUNT, sizeof (fs_cnt), 1,
+                           &fs_cnt);
+                       if (err != ENOENT && err != 0) {
+                               dsl_dir_rele(newparent, FTAG);
+                               dsl_dir_rele(dd, FTAG);
+                               return (err);
+                       }
+
+                       /*
+                        * have to add 1 for the filesystem itself that we're
+                        * moving
+                        */
+                       fs_cnt++;
+
+                       err = zap_lookup(os, dd->dd_object,
+                           DD_FIELD_SNAPSHOT_COUNT, sizeof (ss_cnt), 1,
+                           &ss_cnt);
+                       if (err != ENOENT && err != 0) {
+                               dsl_dir_rele(newparent, FTAG);
+                               dsl_dir_rele(dd, FTAG);
+                               return (err);
+                       }
+               }
+
+               /* no rename into our descendant */
+               if (closest_common_ancestor(dd, newparent) == dd) {
+                       dsl_dir_rele(newparent, FTAG);
+                       dsl_dir_rele(dd, FTAG);
+                       return (SET_ERROR(EINVAL));
+               }
+
+               error = dsl_dir_transfer_possible(dd->dd_parent,
+                   newparent, fs_cnt, ss_cnt, myspace, ddra->ddra_cred);
+               if (error != 0) {
+                       dsl_dir_rele(newparent, FTAG);
+                       dsl_dir_rele(dd, FTAG);
+                       return (error);
+               }
+       }
+
+       dsl_dir_rele(newparent, FTAG);
+       dsl_dir_rele(dd, FTAG);
+       return (0);
+}
+
+static void
+dsl_dir_rename_sync(void *arg, dmu_tx_t *tx)
+{
+       dsl_dir_rename_arg_t *ddra = arg;
+       dsl_pool_t *dp = dmu_tx_pool(tx);
+       dsl_dir_t *dd, *newparent;
+       const char *mynewname;
+       int error;
+       objset_t *mos = dp->dp_meta_objset;
+
+       VERIFY0(dsl_dir_hold(dp, ddra->ddra_oldname, FTAG, &dd, NULL));
+       VERIFY0(dsl_dir_hold(dp, ddra->ddra_newname, FTAG, &newparent,
+           &mynewname));
+
+       /* Log this before we change the name. */
+       spa_history_log_internal_dd(dd, "rename", tx,
+           "-> %s", ddra->ddra_newname);
+
+       if (newparent != dd->dd_parent) {
+               objset_t *os = dd->dd_pool->dp_meta_objset;
+               uint64_t fs_cnt = 0;
+               uint64_t ss_cnt = 0;
+
+               /*
+                * We already made sure the dd counts were initialized in the
+                * check function.
+                */
+               if (spa_feature_is_active(dp->dp_spa,
+                   SPA_FEATURE_FS_SS_LIMIT)) {
+                       VERIFY0(zap_lookup(os, dd->dd_object,
+                           DD_FIELD_FILESYSTEM_COUNT, sizeof (fs_cnt), 1,
+                           &fs_cnt));
+                       /* add 1 for the filesystem itself that we're moving */
+                       fs_cnt++;
+
+                       VERIFY0(zap_lookup(os, dd->dd_object,
+                           DD_FIELD_SNAPSHOT_COUNT, sizeof (ss_cnt), 1,
+                           &ss_cnt));
+               }
+
+               dsl_fs_ss_count_adjust(dd->dd_parent, -fs_cnt,
+                   DD_FIELD_FILESYSTEM_COUNT, tx);
+               dsl_fs_ss_count_adjust(newparent, fs_cnt,
+                   DD_FIELD_FILESYSTEM_COUNT, tx);
+
+               dsl_fs_ss_count_adjust(dd->dd_parent, -ss_cnt,
+                   DD_FIELD_SNAPSHOT_COUNT, tx);
+               dsl_fs_ss_count_adjust(newparent, ss_cnt,
+                   DD_FIELD_SNAPSHOT_COUNT, tx);
+
+               dsl_dir_diduse_space(dd->dd_parent, DD_USED_CHILD,
+                   -dsl_dir_phys(dd)->dd_used_bytes,
+                   -dsl_dir_phys(dd)->dd_compressed_bytes,
+                   -dsl_dir_phys(dd)->dd_uncompressed_bytes, tx);
+               dsl_dir_diduse_space(newparent, DD_USED_CHILD,
+                   dsl_dir_phys(dd)->dd_used_bytes,
+                   dsl_dir_phys(dd)->dd_compressed_bytes,
+                   dsl_dir_phys(dd)->dd_uncompressed_bytes, tx);
+
+               if (dsl_dir_phys(dd)->dd_reserved >
+                   dsl_dir_phys(dd)->dd_used_bytes) {
+                       uint64_t unused_rsrv = dsl_dir_phys(dd)->dd_reserved -
+                           dsl_dir_phys(dd)->dd_used_bytes;
+
+                       dsl_dir_diduse_space(dd->dd_parent, DD_USED_CHILD_RSRV,
+                           -unused_rsrv, 0, 0, tx);
+                       dsl_dir_diduse_space(newparent, DD_USED_CHILD_RSRV,
+                           unused_rsrv, 0, 0, tx);
+               }
+       }
+
+       dmu_buf_will_dirty(dd->dd_dbuf, tx);
+
+       /* remove from old parent zapobj */
+       error = zap_remove(mos,
+           dsl_dir_phys(dd->dd_parent)->dd_child_dir_zapobj,
+           dd->dd_myname, tx);
+       ASSERT0(error);
+
+       (void) strcpy(dd->dd_myname, mynewname);
+       dsl_dir_rele(dd->dd_parent, dd);
+       dsl_dir_phys(dd)->dd_parent_obj = newparent->dd_object;
+       VERIFY0(dsl_dir_hold_obj(dp,
+           newparent->dd_object, NULL, dd, &dd->dd_parent));
+
+       /* add to new parent zapobj */
+       VERIFY0(zap_add(mos, dsl_dir_phys(newparent)->dd_child_dir_zapobj,
+           dd->dd_myname, 8, 1, &dd->dd_object, tx));
+
+       zvol_rename_minors(dp->dp_spa, ddra->ddra_oldname,
+           ddra->ddra_newname, B_TRUE);
+
+       dsl_prop_notify_all(dd);
+
+       dsl_dir_rele(newparent, FTAG);
+       dsl_dir_rele(dd, FTAG);
+}
+
+int
+dsl_dir_rename(const char *oldname, const char *newname)
+{
+       dsl_dir_rename_arg_t ddra;
+
+       ddra.ddra_oldname = oldname;
+       ddra.ddra_newname = newname;
+       ddra.ddra_cred = CRED();
+
+       return (dsl_sync_task(oldname,
+           dsl_dir_rename_check, dsl_dir_rename_sync, &ddra,
+           3, ZFS_SPACE_CHECK_RESERVED));
+}
+
+int
+dsl_dir_transfer_possible(dsl_dir_t *sdd, dsl_dir_t *tdd,
+    uint64_t fs_cnt, uint64_t ss_cnt, uint64_t space, cred_t *cr)
+{
+       dsl_dir_t *ancestor;
+       int64_t adelta;
+       uint64_t avail;
+       int err;
+
+       ancestor = closest_common_ancestor(sdd, tdd);
+       adelta = would_change(sdd, -space, ancestor);
+       avail = dsl_dir_space_available(tdd, ancestor, adelta, FALSE);
+       if (avail < space)
+               return (SET_ERROR(ENOSPC));
+
+       err = dsl_fs_ss_limit_check(tdd, fs_cnt, ZFS_PROP_FILESYSTEM_LIMIT,
+           ancestor, cr);
+       if (err != 0)
+               return (err);
+       err = dsl_fs_ss_limit_check(tdd, ss_cnt, ZFS_PROP_SNAPSHOT_LIMIT,
+           ancestor, cr);
+       if (err != 0)
+               return (err);
+
+       return (0);
+}
+
+timestruc_t
+dsl_dir_snap_cmtime(dsl_dir_t *dd)
+{
+       timestruc_t t;
+
+       mutex_enter(&dd->dd_lock);
+       t = dd->dd_snap_cmtime;
+       mutex_exit(&dd->dd_lock);
+
+       return (t);
+}
+
+void
+dsl_dir_snap_cmtime_update(dsl_dir_t *dd)
+{
+       timestruc_t t;
+
+       gethrestime(&t);
+       mutex_enter(&dd->dd_lock);
+       dd->dd_snap_cmtime = t;
+       mutex_exit(&dd->dd_lock);
+}
+
+void
+dsl_dir_zapify(dsl_dir_t *dd, dmu_tx_t *tx)
+{
+       objset_t *mos = dd->dd_pool->dp_meta_objset;
+       dmu_object_zapify(mos, dd->dd_object, DMU_OT_DSL_DIR, tx);
+}
+
+boolean_t
+dsl_dir_is_zapified(dsl_dir_t *dd)
+{
+       dmu_object_info_t doi;
+
+       dmu_object_info_from_db(dd->dd_dbuf, &doi);
+       return (doi.doi_type == DMU_OTN_ZAP_METADATA);
+}
+
+#if defined(_KERNEL) && defined(HAVE_SPL)
+EXPORT_SYMBOL(dsl_dir_set_quota);
+EXPORT_SYMBOL(dsl_dir_set_reservation);
+#endif